The following are the proposed studies to be conducted: 1. To determine the corneal diffusion rate of topically applied phenylephrine with and without an intact epithelium, and to establish if it is metabolized or does breakdown product form as it diffuses across the cornea. These studies will establish whether it is phenylephrine, metabolite or breakdown product that causes the drug induced edema. 2. To determine the soluble proteins of the cornea and to establish how they are altered in corneal edema. 3. To determine if Ca ion free solutions, thiol-oxidation of intracelluar glutathione, and pH alter the corneal endothelial surface membrane proteins. 4. To determine total corneal calcium, and the calcium concentration in the corneal component layers. Corneal endothelial mitochondrial calcium will also be measured. These values will be compared to corneal endothelial and stromal calcium following perfusion of calcium free media. 5. To develop the technique of ouabain and carbonic anhydrase binding to the corneal endothelium of rabbit and human. Specifically, we will determine if the binding sites are increased or decreased during age and stress. 6. To measure the corneal swelling pressure and to correlate this to the degree of corneal edema (water content) proteoglycan release from the corneal stroma and aggregation of stromal collagen fibers. 7. To develop the technique of using fluorescent labels to probe the thiol groups on and in the corneal endothelium, and to establish their role in the maintenance of the endothelial barrier and pump function.